keach: barbour's curiosity led him to the modern science of fingerprints where he discovered that with a large enough sample he might be able to discern the gender of the person who made the print. males have wider ridges. females have narrower ones. through trial and error, he devised a technique to make permanent molds of the fingerprints. from these he began to construct a sample. finally, an intriguing discovery -- direct evidence that one set of workers was being replaced by another. barbour: it appears that the early handmade figurines were made by females. after the establishment of apartment compounds in teotihuacan about 250 a.d., you get a shift to wider ridges on the late handmade figurines and the early moldmade figurines. so it appears that when you have the development of the apartment compound that males come into the industry. keach: so as the city grew, the figurine industry changed. initially worked by women, probably as part of their domestic duties, it became a separate full-time specialization performed by men. with men moving into industry and doing less farm work